On the characterisation of tracer particles for thermographic particle image velocimetry

Characterisation of the luminescence properties of BAM:Eu2+ particles as a tracer for thermographic particle image velocimetry

“…3.1. Results presented in our recent study [14] indicated that at a fluence of 23 mJ/cm 2 and at room temperature, a seeding density of 10 11 particles per m 3 resulted in a pixel intensity of 200 counts in the 464-40 channel. From this result, it can be estimated that a single BAM:Eu 2+ particle emits on average 3 × 10 6 luminescence photons following a single laser pulse.…”

“…The particle-counting system is identical to that described in [14]. Only a brief description is given here.…”

“…Using a 355 nm long-pass dichroic mirror and a cylindrical lens (+750 mm), a thin light sheet (160 μm) was formed along the same optical path as the 355 nm light sheet. High-resolution particle images recorded using an interline transfer CCD camera (Imager Intense, LaVision, 1376 × 1040 pixels, 6.45 μm pixel size) were then processed in MATLAB in order to evaluate the number of local maxima, which is used as a measure of the number of particles as described in [14].…”

“…As discussed in [14], investigations must be performed in the gas phase and not in aggregated powder form where the effects of multiple scattering dominates and where the particles probed are subjected to a repeated illumination, which could accentuate particle heating and/or lead to damage. However, because it is difficult to set, control and reproduce seeding conditions in the gas phase, the number density of particles must be measured in situ in order to determine the emission characteristics of phosphor particles on a per-particle basis.…”

“…However, because it is difficult to set, control and reproduce seeding conditions in the gas phase, the number density of particles must be measured in situ in order to determine the emission characteristics of phosphor particles on a per-particle basis. In our previous work [14], a particlecounting system was developed and demonstrated, allowing the simultaneous measurement of seeding density and [13] signal level for various conditions. By correcting for variations of seeding density, the influence of other parameters on the collected phosphorescence intensity can be isolated.…”